Fuel control system using rf circuits

ABSTRACT

Apparatus for controlling the injection of fuel in an internal combustion engine utilizes RF circuits including a tuneable RF detector responsive to the speed of the engine.

United States Patent Cinquegrani [5 4] FUEL CONTROL SYSTEM USING RF CIRCUITS [72] Inventor: Vincent J. Cinquegrani, 333 West Second Street, Scottsdale, Ariz.

22 Filed: March 22, 1971 21 Appl. 190.; 126,694

, [52] US. Cl. ..l23/32 EA, 123/32 R, 123/139 E [51] Int. Cl. ..F02b 3/00, F02m 39/00 [58] Field of Search ..123/32 EA, 139 E [56] References Cited UNITED STATES PATENTS 2,949,900 8/ l 960 Bodine 1 23/32 Oct. 24, 1972 Endo ..l23/32 EA Moss ..l23/32 EA Primary Examiner-Laurence M. Goodridge Assistant ExaminerRonald B. Cox Attorney-H. Gordon Shields [57] ABSTRACT 18 Claims, 5 Drawing Figures p12 FM FF 050444702 4ND AMPl/F/EE ,16 25292 1? ssA/smme WW6 N0 PULS'ES' flMPZ/f/EE FUEL CONTROL SYSTEM USING RF CIRCUITS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to fuel control systems for internal combustion engines. More particularly, this invention relates to electronic systems for controlling the injection of fuel in internal combustion engines according to the speed of the engine by varying the length of time fuel is admitted into an intake duct or into a combustion chamber and to the control of the pressure of the injected fuel.

2. Description of the Prior Art:

There have been many systems designed for injecting proper quantities of fuel into internal combustion engines. The prior art, with respect to electronic fuel injection systems, includes many different approaches, such as coupled inductor circuits in which current is varied by Potentiometers, transistorized multivibrator systems utilizing variable time delays in which the time delay varies according to mechanical linkage associated with the speed of the engine or according to a variable resistance also associated with the speed of the engine, and electronic systems using variable voltage outputs which vary directly with the speed of the engine to control the timing of fuel injectors. Typically, a monostable multivibrator is used in prior art devices. Associated with the monostable vibrator are timing means of various types used to trigger the vibrator and thus control the length of time a fuel injection solenoid is open to allow a flow of fuel therethrough.

Under various operating conditions of an internal combustion engine, among which the primary condition is the speed of the engine, various amountsof fuel are required for optimum efficiency of the engine. Accordingly, it is desired to provide the proper amount of fuel to an engine under any and all operating conditions to which the engine may be subjected. Fuel is typically injected into an intake manifold through an injector nozzle, or, more accurately with respect to a multicylinder engine, through a plurality of injector nozzles or valves, with normally one nozzle or valve per cylinder. The amount of fuel flowing through each nozzle is a function of the pressure of the fuel at the nozzle and the length of time, or duration, that the nozzle is open.

In prior art devices the control of the nozzle opening time duration is by electronic timing signals or pulses which actuate solenoid valves at the nozzles. Such control is accomplished by means of the circuits and devices mentioned above. One of the deficiencies of such prior art devices is their lack of sufficient flexibility to meet required and/or desired conditions. In other words, the fuel control systems, once installed, are usually fixed with respect to their response to speed, temperature conditions, and any other parameters which may be used as operating functions.

The control of the pressure of the fuel is typically accomplished in either of two ways, first, a constant fuel pressure may be used, or second, a variable fuel pressure may be used in which the pressure is a direct function of the speed of the engine. Prior art devices do not include means for varying the fuel pressure according to engine requirements with respect to the timing of the fuel injection nozzles.

As indicated above, electronic fuel injection systems of the prior art vary the timing of the fuel at the nozzle. If the fuel pressure is varied, it is varied directly as a function of the speed of the engine. While these- SUMMARY OF THE INVENTION The invention herein described and claimed comprises a fuel control system for an internal combustion engine. Tuned RF circuits are used to control the length of time during'which fuel is injected into the engine and the pressure at which the fuel is injected.

The following are among the objects of this invention:

to provide a new anduseful fuel control system;

to provide a new and useful fuel control system for an internal combustion engine;

to provide a new and useful fuel control system using tuned RF circuits;

to provide a new and useful fuel control system'for varying the length of time during which fuel is injected;

to provide a new and useful fuel control system for varying the pressure at which fuel is injected;

to provide a new and useful fuel control system for varying the timing and pressure of fuel as it is injected into an internal combustion engine;

to provide new and useful tuned circuits for fuel control systems; i

to provide new and useful electronic circuits for predeterminably controlling the injection of fuel in an internal combustion engine; and

to provide new and useful apparatus for adjustably varying the duration and pressure of injected fuel in an internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a block diagram of a fuel control system.

FIG. 2 is a schematic diagram of a portion of the fuel control system of FIG. 1.

FIG. 3 is a schematic diagram of another embodiment of a portion of the fuel control system of FIG. 1.

FIG. 4 is a schematic diagram showing variations of tuned circuits.

FIG. 5 is a schematic diagram showing another variation of tuned circuits.

DESCRIPTION OF THE PREFERRED EMBODIMENT The fuel control system described herein comprises two portions. The first portion is characterized by electronic circuitry and controls for the timing of fuel for injection into an engine through a plurality of fuel nozzles. The second portion is characterized by electronic circuitry cooperating with the fuel supply to provide fuel at the nozzles at a proper, predetermined pressure.

appropriate and well known means for determining the speed of the engine in terms of revolutions per unit of time, such as revolutions per minute. Such transducers may typically be electrically connected to the distributor or the coil, butmay also be of a mechanical or any other design, if desired, which includes some form of electronic output corresponding to the speed of the engme.

Engine speed signals from transducer are fed to an FM RF oscillator and amplifier 12. As with the transducer 10, the FM RF oscillator and amplifier 12 may be of any state-of-the-art design. The engine speed signals from transducer 10, normally in the form of an analog voltage, are sent to FM RF oscillator unit 12. The output of the oscillator is modulated according to the speed of the engine as indicated by the output of transducer 10. Under present technology, the frequency or frequencies available or practical depend on size and cost limitations, and may be in the range of 25,000 cycles per second (25 KHz) to 250 million cycles per second (250 MHz). Typically, the RF oscillator may operate at a resonant frequency range of between about 1 and 1.3 MHz. it is obvious that any suitable frequency may be used. In the present embodiment, the RF output signal is preferably frequency modulated.

After modulation, the output signal is amplified and transmitted to an adjustable RF detector 14, which will be discussed in detail below. The adjustable RF detector comprises tuned circuits coupled so as to respond in a predetermined manner to the output of the FM RF oscillator and amplifier 12. The concepts of the terms adjustable and predetermined are used to indicate that adjustments may be made on any given or particular engine according to the specific operating characteristics of that engine. Thus, rather than a one-time only factory calibration, the present fuel control system may be calibrated and adjusted on. any engine to any desired operating characteristics and parameters. Moreover, the present system may be calibrated to follow a plurality of fuel demand curves of substantial complexity, as compared to prior art devices capacity or ability to follow only simple curves. For example, the present invention can follow full load and part load curves, each different and independent from each other.

The output of the detector 14, which may also be considered as an adjustable RF memory system, is transmitted to a modulated pulse generator and amplifier l6 and to a fuel pump pressure control amplifier 22. The modulated pulse generator and amplifier l6 first generates a preferably square wave pulse, the width of which varies according to the input signal from the RF detector 14. The pulses are then amplified and are in turn used to actuate solenoid valves which control the flow of fuel through fuel nozzles 20. Each fuel nozzle solenoid valve is held open for a length of time corresponding to the width of the pulse. It will be noted that only one nozzle is schematically illustrated in FIG. 1, and fuel is illustratively shown as being discharged or sprayed therefrom.

The output pulses of the pulse generator and amplifier 16 are triggered according to engine timing signals, again typically in the form of pulses, which are fed to the generator and amplifier 16 from a source denoted by block 18. The engine timing pulse preferably may be taken from the distributor or coil in a well known manner.

Other factors may be included within block 18 to modulate or vary the output therefrom. These factors may be taken into consideration to modify the input to the pulse generator and amplifier'l6. These may be any other engine operating parameters, such as engine temperature, ambient temperature, exhaust temperature, barometric pressure, and any other factors which could or should be used to influence 'the timing of the fuel solenoids with respectto eitherthe determination of when they open or the duration or length of time that they stay open.

Output signals from the adjustable RF memory system 14 are also sent to a fuel pump pressure control amplifier 22 by a conductor 21. The output of the amplifier 22 varies according in predetermined manner according to the output of the RF memory system 14 and also according to fuel pressure transducer 28. Fuel from fuel supply 30 flows to fuel pump 26 through his] line or conduit 25. Fuel pump 26 is preferably driven by a variable speed electric motor 24. Fuel is delivered from fuel pump 26 to the fuel nozzles 20 through fuel line or conduit 27 A fuel pressure line 29 extends from fuel line 27 to fuel pressure transducer 28. The fuel pressure transducer 28, whichmay be of any conventional design, senses the pressure of the-fuel and sends its output signal, corresponding to the pressure of the fuel, to the fuel pressure control amplifier 22 as a feedback signal. The output of the fuel pump pressure control amplifier 22 is in turn used to control the speed of the electric fuel motor 24 and ultimately the fuel pressure of the fuel through fuel line 27.

It may thus be seen that the pressure of the fuel delivered to the nozzles may be controlled according to the speed of the engine as modulated or as responsive to the output of the adjustable RF memory system 14. The timing of the nozzles, the length of time that each one of them stays open to deliver fuel to a cylinder, is also controlled by, or is responsive to, the output of the adjustable RF memory system 14, as modulated by en gine timing pulses and any other desired parameters, such as atmospheric (barometric) pressure, ambient air temperature, engine temperature, exhaust tempera ture, and the like.

FIG. 2 shows in detail the'circuitry associated with the adjustable RF memory system 14. A plurality of tuned circuits 40, 40a, 40b, 40c, and 40d, are shown in series. The output from FM RF oscillator and amplifier 12 is sent to the tuned circuits 40a 40d through conductor 13. Each of the tuned circuits 40a 40d is typically an inductance-capacitance circuit, comprising a variable resistance 42, which may typically be a potentiometer, in parallel with an inductor 43. Another inductor 44, coupled to inductor 43, may typically be arranged in parallel with .aresistor 46 and a variable capacitor 48. As illustrated in FIG. 2, the inductors of the primary of each of the tuned circuits are shown coupled together in series by conductors 45, a, 45b, and 450, respectively. Supply voltage is typically provided to the circuits through conductor 50. The secondary of each of the tuned circuits, that is, the inductor 44, resistor 46, and variable capacitor 48, are, for each circuit, serially connected through conductors 47, 47a,

47b, and 47c. The secondaries are then terminated to ground through conductor 49. The tuned circuits include variable capacitors 48, 48a, 48d and are tunable to cover the frequency range of the FM RF oscillator 12.

The tuned circuits are adjustable to cover the frequency range sequentially according to voltage output of the engine RPM transducer as manifested by the RF output of the FM RF oscillator. The output from the tuned circuits responds to RF input according to desired adjustments of the potentiometers 42, 42a, 42d. In that manner, any desired curve may be described to follow the required and desired engine demands. While five tuned circuits are shown in FIG. 2, it will be obvious that the number may vary to only a single tuned circuit, depending on the performance desired. The number shown may provide optimum flexibility and engine performance.

The output from the tuned circuits through conductor 51 is rectified by diode 52 in conductor 51 and appears as a dc voltage through a variable resistor 58. Variable resistor 58 is connected in parallel by conductor 53 with a filter capacitor 54 in conductor 55 and is terminated to ground through conductor 56. Conductor 21, which extends between memory system 14 and fuel pump pressure control amplifier 22, preferably connects with conductor 53 ahead of variable resistor 58. Accordingly, the fuel pump pressure is modulated according to the speed of the engine.

The load on the engine, as manifested by engine vacuum through a conduit 70, is also used to modulate or to determine the output of the adjustable RF detector 14 by modulating the dc output voltage at resistance 58. A cylinder 60 is connected to engine vacuum conduit 70. A compression spring 62 within the cylinder 60 biases a diaphragm 64 which closes the cylinder 60 and comprises an end wall for the cylinder opposite that to which conduit 70 is connected. A sensing arm 66 is connected to diaphragm 64 and moves according to the deflection of the diaphragm 64, which in turn depends on the engine vacuum within cylinder 60. Conductor 15 is carried by, or is secured to, sensing arm 66, and extends from variable resistor 58 to the modulated pulse generator and amplifier 16. Thus the output through the resistor 58 is varied by the engine vacuum as conductor 15 moves according to the deflection of diaphragm 64 and sensing arm 66. Resistor 58 and conductor 15 comprise simply a load control potentiometer which is varied according to the deflection of sensing arm 66, which in turn reflects the load on the engine according to manifold vacuum. Also shown in FIG. 2 as an input to the modulated pulse generator and amplifier 16 is conductor 17, which feeds timing pulses and other parameters into the generator and amplifier 16. The conductor 21, which extends between conductor 53 and fuel pump pressure control amplifier 22, could be connected to conductor 15 and the fuel pressure would accordingly be modulated according to both the engine speed and engine load.

Each of the tuned circuits is adjusted or tuned to respond to different resonant frequencies or signals from the FM RF oscillator and amplifier 12, which in turn responds to the speed of the engine as detected by the engine RPM transducer 10. Thus as the speed of the engine changes, the frequency of the FM RF oscillator also varies, and the various circuits of the RF memory respond to give an output to the modulated pulse generator and amplifier which in turn varies the timing, that is, the opening and the closing, of the fuel solenoids and accordingly varies the amount of fuel, at the predetermined pressure, that is discharged through each fuel nozzle. Each tuned circuit may be varied as desired according to the setting of the variable resistor or potentiometer 42, 42a, etc., over the entire speed range of the engine. Since each of the tuned circuits is variable, it may readily be seen that the response of the engine to the proper amount of fuel may be controlled to an extremely finite degree. It has been found that a minimum of one tuned circuit is required, as previously indicated, and that two circuits are needed for good operation. Three, four, or five such tuned circuits are desirable for optimum operation of an engine. For illustrative purposes, five such tuned circuits have been shown in FIG. 2. It will be noted that each of the tuned circuits is of a well known inductance-capacitance type, in which the resistance is varied to change voltage output, and the capacitance is varied to tune the circuit.

Since each tuned circuit of the RF memory may be adjusted, the unit provides a different and a desired output corresponding to various specific input signals. Or, in other words, in response to a specific input signal, which is determined by the speed of the engine, the output from each tuned circuit of the RF memory system may be adjusted to provide a predetermined output signal. That output signal is in turn used'to modulate or vary the width of pulses which determine the opening and the closing and thus the timing of fuel solenoids. The term memory is used to denote the ability of the tuned circuits to resonate at predetermined frequencies over a given frequency range according to the speed of the engine and to the specific adjustments for each of the tuned circuits. The output of each tuned circuit accordingly varies as desired in a predetermined manner according to the speed of the engine as manifested by the frequency modulated RF signal from the oscillator 12. Thus, each circuit may be tuned to a different resonant frequency and the output of each circuit may be varied as desired at that resonant frequency. Once adjusted, the tuned circuits remember and respond with a given or specific output according to any given or specific input.

The adjustable RF memory detector system provides a means for varying and thus controlling the amount of fuel provided by the fuel nozzles to the cylinders of an internal combustion engine according to the specific needs of the engine throughout the speed or RPM operating range of the engine. This, of course, comprises the compensation of the engine for the differences in its volumetric efficiency at all operating speeds. The volumetric efficiency of an engine may briefly be defined as the ratio of the volume of the fuel/air charge, inducted into an engine at atmospheric pressure, to the piston displacement of the engine.

Since the volumetric efficiency of an engine varies throughout the speed range of the engine in a predeterminable manner, it is accordingly desirable to compensate for the volumetric efficiency throughout the speed range. With the herein described apparatus, such compensation may be accomplished.

In addition to compensating the engine for volumetric efficiency, the present fuel control system also compensates the engine for load conditions as indicated by manifold vacuum. Resistor 58 and conductor 15 comprise a load control potentiometer varied according to the engine vacuum. The engine vacuum through conduit 70 exerts a force on diaphragm 64 from within cylinder 60 and movement of the diaphragm moves conductor 15 on resistor 58.

Under no load conditions, which result in high engine'vacuum, the diaphragm 64 would be displaced or deflected a maximum amount. This would result in a decrease in the voltage tapped or sensed along resistor 58 by conductor 15 and a decrease in the voltage output from the RF memory system 14 to the modulated pulse generator and amplifier 16. At high load conditions, which result in low engine vacuum, deflection of diaphragm 64 is minimal, or negligible, and the output from the tuned circuits of the RF memory system is maximum through the load control potentiometer. The output of the tuned circuits through the load control potentiometer may range from 25 percent at no load conditions to 100 percent at fuel load conditions.

The adjustable RF memory system, including the load'control potentiometer, may be adjusted to follow a plurality of complex curves required by an engine throughout a wide range of both speed and load variations.

FIG. 3 shows a variation of the adjustable RF circuits of FIG. 2 in which two circuit units, each comprising three stages of tuned circuits, are connected in parallel between the FM RF oscillator 12 to the potentiometer S8 and conductor 15. A separate input to each of the units from the oscillator 12 is shown, and each of the units has a 12 volt source connected to the primary of each tuned circuit. It will be noted that for simplicity, thevariable resistors or potentiometers and inductors in the primary of each tuned circuit stage are shown connected together and each inductor, resistor, and variable capacitor in each stage of the secondary are shown connected together directly, in a manner which is equivalent of that shown in FIG. 2, rather than by conductors 45, 450, etc., and conductors 47, 47a, etc. It will also be noted that each unit in FIG. 3 includes a diode 52 and 252, respectively, and a filter capacitor 54 and 254, each of which is terminated to ground. The load control potentiometer 58 is terminated to ground through resistor 259. The first unit 140 comprises the first tuned circuit, which includes potentiometer 142, primary inductor 143, secondary inductor 144, resistor 146, and variable capacitor 148, and the second and third a and b tuned circuits, comprising, respectively, potentiometers 142a, 1421:, and their respective associated components, some of whose reference numerals have been omitted for convenience and clarity, including the primary and secondary inductors and resistors. The variable capacitors 148a and 148b are shown. The second unit 240 includes potentiometers 242, 242a, 242b, primary inductors 243 243b, seconjust the opposite for unit 140, which has 100 percent I effect at full load and percent effect at no load. The

same resonant frequency of corresponding tuned circuit stages for each unit gives different voltage outputs through the potentiometer 58. The different voltages then correspond to the load conditions.

FIG. 4 discloses two tuned circuit stages, as from the embodiment of FIG. 2, and illustrates two different types of tuned circuits, both of which are well known in the art. The first tuned circuit 340 shows the tuned circuit utilized in both FIGS. 2 and 3, in which a variable resistor or potentiometer 342 is used to vary the output at a particular frequency and a variable capacitor 348 is used to tune the circuit. The primary inductor 343,

secondary inductor 344 and resistor 346 correspond to the respective .components in FIGS. 2 and 3. The second stage of FIG. 4 shows another type of tuned circuit 440 in which the output is controlled by varying the coupling between inductors 443 and 444, and, ac-

cordingly, fixed resistor 442 is used in the primary circuit. While both circuits produce substantially similar results and are therefore the substantial equivalents with respect to the present invention, the type of tuned circuit used in the first stage 340, utilizing the potentiometer, is preferred. Resistor 446 and variable capacitor 448 correspond to the respective components in FIGS. 2 and 3 and in tuned circuit 340.

FIG. 5 illustrates another embodiment showing two stages of tuned circuits 540 and 640 which may be utilized in the present invention. Separate amplifiers are shown for each tuned circuit stage. Instead of using one amplifier for all tuned circuits, as illustrated in FIG. 1, individual amplifiers, such as amplifying transistors 524 and 626, may be used for each tunedcircuit, with separate RF inputs through resistors 520 and 620 tocircuits are tuned by variable inductors 544 and 644,

respectively, and capacitors 548 and 648 are accordingly of a fixed value. Secondary resistors 546 and 646 are the same as previously illustrated. Each circuit 540 and 640 includes a 12*volt source, and the secondaries are connected together as previously illustrated.

The output from the tuned circuits is through diode .tromagnetically actuable fuel fuel pump. Under such circumstances constant width pulses may be used to control the timing of the fuel nozzles. Similarly, continuous flow nozzles may be used, the pulse generator 16 may be eliminated, and the fuel may be entirely controlled by the fuel pump. It is also obvious that one or more tuned circuit units could be added to the embodiment of FIG. 3 with inputs tapped into potentiometer 58 in addition to the inputs at either 'end of the potentiometer, as shown.

What is claimed is: 1. A fuel control system for an internal combustion engine having a fuel supply and at least a single elec nozzle connected therewith, comprising, in combination:

means responsive to the speed of the engine for providing an RF signal;

tuned circuit means responsive to the RF signal for providing an output voltage at resonant frequencies; and

a pulse generator responsive to the voltage from the tuned circuit means for generating a pulse to control the electromagnetically actuable fuel nozzle and the flow of fuel therethrough.

2. The fuel control system of claim 1 in which the means responsive to the speed of the engine includes means for sensing the speed of the engine.

3. The fuel control system of claim 2 in which the means responsive to the speed of the engine further includes a frequency modulated radio frequency oscillator.

4. The apparatus of claim 3 in which the RF signal is frequency modulated according to the speed of the engine.

S. The fuel control system of claim I in which the tuned circuit means comprises at least a single adjustable tuned circuit for resonating at a predetermined frequency.

6. The apparatus of claim 5 in which the tuned circuit means includes means for varying the output voltage of the circuit.

7. The fuel control system of claim 1 in which the tuned circuit means includes engine load responsive means to modulate the voltage from the tuned circuit means.

8. The apparatus of claim 7 in which the engine load responsive means comprises:

a cylinder;

conduit means connecting the cylinder to a source of engine vacuum;

diaphragm means associated with the cylinder and displaceable in response to engine vacuum within the cylinder; circuit means for receiving the voltage from the tuned circuit; and means connecting the diaphragm means to the circuit means for modulating the voltage from the circuit means in response to displacement of the diaphragm means. 9. The apparatus of claim 8 in which the circuit means for receiving the voltage from the tuned circuit com prises a potentiometer.

1 The apparatus of claim 9 in which the tuned circuit means comprises a plurality of tuned circuits, each of which is adjustable as to output and resonant frequency.

11. The apparatus of claim 10 in which the plurality of tuned circuits comprise two units of tuned circuits.

12. The apparatus of claim 11 in which each unit of tuned circuits is separately connected to the potentiometer at opposite ends thereof.

13. The apparatus of claim 1 in which the tuned -circuit means includes a plurality of tuned circuits, each of which is tuneable to a different resonant frequency, and the output from each of which is variable, for responding each according to a desired RFsignal.

14. The apparatus of claim 13 in which each tuned circuit includes an amplifier.

15. A fuel control system for an internal combustion engine, comprising, in combination:

means for producing a radio frequency signal in response to the speed of the engine; 7

an adjustable radio frequency memory system responsive to the radio frequency signal for providing a variable voltage;

a pulse generator for providing variable width pulses according to the voltage from the radio frequency memory system;

a fuel supply;

at least a single fuel nozzle connected to the fuel supply and actuable in response to pulses from the pulse generator; and

fuel pressure means responsive to the variable voltage from the radio frequency memory system for controlling the pressure of fuel from the fuel supply to the fuel nozzle.

16. The apparatus of claim 15 in which the pulse generator is also responsive to a plurality of desired engine parameters.

17. The apparatus of claim 15 in which the memory system includes means for varying the voltage therefrom according to the engine vacuum pressure.

18. The apparatus of claim 15 in which the fuel pressure means includes a fuel pump connected to the fuel supply and to the nozzle and a fuel pump pressure control amplifier responsive to the voltage from the memory system for controlling the speed of the fuel pump. 

1. A fuel control system for an internal combustion engine having a fuel supply and at least a single electromagnetically actuable fuel nozzle connected therewith, comprising, in combination: means responsive to the speed of the engine for providing an RF signal; tuned circuit means responsive to the RF signal for providing an output voltage at resonant frequencies; and a pulse generator responsive to the voltage from the tuned circuit means for generating a pulse to control the electromagnetically actuable fuel nozzle and the flow of fuel therethrough.
 2. The fuel control system of claim 1 in which the means responsive to the speed of the engine includes means for sensing the speed of the engine.
 3. The fuel control system of claim 2 in which the means responsive to the speed of the engine further includes a frequency modulated radio frequency oscillator.
 4. The apparatus of claim 3 in which the RF signal is frequency modulated according to the speed of the engine.
 5. The fuel control system of claim 1 in which the tuned circuit means comprises at least a single adjustable tuned circuit for resonating at a predetermined frequency.
 6. The apparatus of claim 5 in which the tuned circuit means includes means for varying the output voltage of the circuit.
 7. The fuel control system of claim 1 in which the tuned circuit means includes engine load responsive means to modulate the voltage from the tuned circuit means.
 8. The apparatus of claim 7 in which the engine load responsive means comprises: a cylinder; conduit means connecting the cylinder to a source of engine vacuum; diaphragm means associated with the cylinder and displaceable in response to engine vacuum within the cylinder; circuit means for receiving the voltage from the tuned circuit; and means connecting the diaphragm means to the circuit means for modulating the voltage from the circuit means in response to displacement of the diaphragm means.
 9. The apparatus of claim 8 in which the circuit means for receiving the voltage from the tuned circuit comprises a potentiometer.
 10. The apparatus of claim 9 in which the tuned circuit means comprises a plurality of tuned circuits, each of which is adjustable as to output and resonant frequency.
 11. The apparatus of claim 10 in which the plurality of tuned circuits comprise two units of tuned circuits.
 12. The apparatus of claim 11 in which each unit of tuned circuits is separately connected to the potentiometer at opposite ends thereof.
 13. The apparatus of claim 1 in which the tuned circuit means includes a plurality of tuned circuits, each of which is tuneable to a different resonant frequency, and the output from each of which is variable, for responding each according to a desired RF signal.
 14. The apparatus of claim 13 in which each tuned circuit includes an amplifier.
 15. A fuel control system for an internal combustion engine, comprising, in combination: means for producing a radio frequency signal in response to the speed of the engine; an adjustable radio frequency memory system responsive to the radio frequency signal for providing a variable voltage; a pulse generator for providing variable width pulses according to the voltage from the radio frequency memory system; a fuel supply; at least a single fuel nozzle connected to the fuel supply and actuable in response to pulses from the pulse generator; and fuel pressure means responsive to the variable voltage from the radio frequency memory system for controlling the pressure of fuel from thE fuel supply to the fuel nozzle.
 16. The apparatus of claim 15 in which the pulse generator is also responsive to a plurality of desired engine parameters.
 17. The apparatus of claim 15 in which the memory system includes means for varying the voltage therefrom according to the engine vacuum pressure.
 18. The apparatus of claim 15 in which the fuel pressure means includes a fuel pump connected to the fuel supply and to the nozzle and a fuel pump pressure control amplifier responsive to the voltage from the memory system for controlling the speed of the fuel pump. 